Glass composition for low temperature sintering, glass frit, dielectric composition and multilayer ceramic capacitor using the same

ABSTRACT

The invention relates to a glass composition and a glass frit adequate for low temperature sintering agent at 1,100° C. or less, and a dielectric composition and a multilayer ceramic capacitor using the same. The glass composition comprises aLi 2 O-bK 2 O-cCaO-dBaO-eB 2 O 3 -fSiO 2 , in which a, b, c, d, e and f satisfy following relationships: a+b+c+d+e+f=100, 2≦a≦10, 2≦b≦10, 0≦c≦25, 0≦d≦25, 5≦e≦20, and 50≦f≦80.

CLAIM OF PRIORITY

This application claims the benefit of Korean Patent Application No.2005-69342 filed on Jul. 29, 2005, in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a glass composition, a glass frit, adielectric composition and a multilayer ceramic capacitor using thesame, and more particularly to a borosilicate system glass frit, whichhas high specific surface area, excellent high temperature fluidity andhigh solubility for BaTiO₃, a composition thereof, a dielectriccomposition containing the same and a multilayer ceramic capacitor usingthe same.

2. Description of the Related Art

Recently, along with rapid development in electric and electronicappliances for miniaturization, light weight, high performance and soon, multilayer ceramic capacitors used therein are also facing demandsfor smaller size and larger capacitance. In order to realize smallersize and larger capacitance, dielectric layers of such a multilayerceramic capacitor are getting thinner while being stacked by a greaternumber. At present, BaTiO₃ dielectric layers are stacked by 470 layersor more with a thickness of 3 g or less in order to realize a capacitorhaving an ultra high capacitance. Occasionally, a dielectric layerhaving a thickness of 2 μm or less is also demanded. In order to producesuch a multilayer ceramic capacitor having an ultra high capacitancewith a greater number of dielectric layers stacked on atop another, itis critical to make the dielectric layers as thin as possible. As thedielectric layers are getting thinner, a uniform micro-structure hasbecome the most important factor to ensure in order to realizedielectric characteristics and reliability.

In addition to thin dielectric layers, continuity of internal electrodesalso act as a very important factor to ensure in order to realize thecapacitance of a multilayer ceramic capacitor. Ni electrode layersgenerally used for internal electrodes have a sintering temperaturelower for about several hundred ° C. than that of ceramic dielectricmaterial. Thus, sintering performed at a too high temperature increasesthe sintering shrinkage difference between the internal electrode layersand the dielectric layers, thereby causing delamination. Furthermore,heat treatment (sintering) performed at a high temperature leads toquick conglomeration of the Ni electrode layer, thereby causingelectrode discontinuity. This as a result degrades capacitance whileincreasing short ratio. Therefore, in order to prevent such problems, itis preferable to sinter the Ni internal electrodes and the ceramicdielectric layers at a low temperature of 1,100° C. or less in areducing atmosphere.

Furthermore, multilayer ceramic capacitors need a thermally stablecapacitance in order to achieve high quality performance. The multilayerceramic capacitors, according to their use, are required to satisfy X5Rdielectric characteristics defined by the Electronic Industries Alliance(EIA) standard. According to this standard, capacitance variation (AC)should be ±15% or less at a temperature ranging from −55° C. to 85° C.(reference temperature 25° C.).

As conventional sintering agents used for fabrication of multilayerceramic capacitors, BaO—CaO—SiO₂ system glass frit and BaSiO₃ systemmixture powder are typically used. However, such sintering agents rarelypromote sintering at a low temperature of 1,150° C. or less owing totheir high melting point of 1,200° C. or more. Furthermore, such aconventional vitreous sintering agent accelerates liquid formation at ahigh temperature, which disadvantageously narrows a sinteringtemperature range for the fabrication of a multilayer ceramic capacitor.Japanese Patent Application Publication No. 2000-311823 discloses (Ba,Ca)_(x)SiO_(2+x), where x=0.8 to 1.2, as a sintering agent for thefabrication of a multilayer ceramic capacitor. However, dielectriclayers containing such sintering agent disclosed in this document have asintering temperature exceeding 1,100° C. Thus, with the sintering agentdisclosed in this document, it is difficult to produce a multilayerceramic capacitor having ultra thin dielectric layers.

SUMMARY OF THE INVENTION

The present invention has been made to solve the foregoing problems ofthe prior art and therefore an object of certain embodiments of thepresent invention is to provide a glass composition for a lowtemperature sintering and a glass frit consisting of the same, by whichBaTiO₃ dielectric material can be sintered uniformly at a lowtemperature of 1,100° C. or less and X5R dielectric characteristic canbe satisfied.

Another object of certain embodiments of the present invention is toprovide a dielectric composition using the glass composition of theinvention which can be sintered at a low temperature of 1,100° C. orless while satisfying X5R dielectric characteristics.

Further another object of certain embodiments of the present inventionis to provide a multilayer ceramic capacitor using the dielectriccomposition of the invention which can be fabricated by low temperaturesintering at 1,100° C. or less while showing X5R dielectriccharacteristics.

According to an aspect of the invention for realizing the object, thereis provided a glass composition comprisingaLi₂O-bK₂O-cCaO-dBaO-eB₂O₃-fSiO₂, in which a, b, c, d, e and f satisfyfollowing relationships: a+b+c+d+e+f=100, 2≦a≦10, 2≦b≦10, 0≦c≦25,0≦d≦25, 5≦e≦20, and 50≦f≦80.

In the glass composition of the invention, it is preferable that a, b,c, d, e and f satisfy following relationships: 3≦a≦8, 2≦b≦5, 0≦c≦15,0≦d≦15, 10≦e≦20, and 55≦f≦75. More preferably, a, b, c, d, e and fsatisfy following relationships: 3≦a≦8, 2≦b≦5, 0≦c≦15, 5≦d≦15,12.5≦e≦17.5, and 60≦f≦75.

According to another aspect of the invention for realizing the object,there is provided a glass frit of a glass composition expressed by aformula: aLi₂O-bK₂O-cCaO-dBaO-eB₂O₃-fSiO₂, where a+b+c+d+e+f=100,2≦a≦10, 2≦b≦10, 0≦c≦25, 0≦d≦25, 5≦e≦20, and 50≦f≦80, the glass fritcomprising ultra fine spherical powder having a particle size rangingfrom 100 nm to 300 nm.

In the glass frit of the invention, it is preferable that a, b, c, d, eand f satisfy following relationships: 3≦a≦8, 2≦b≦5, 0≦c≦15, 0≦d≦15,10≦e≦20, and 55≦f≦75. More preferably, a, b, c, d, e and f satisfyfollowing relationships: 3≦a≦8, 2≦b≦5, 0≦c≦15, 5≦d≦15, 12.5≦e≦17.5, and60≦f≦75.

According to further another aspect of the invention for realizing theobject, there is provided a dielectric composition comprising: a maincomponent of BaTiO₃; and sub-components containing the above-mentionedglass composition of the invention, in which the sub-componentscomprise, based on 100 mole of the main component, 1.0 to 3.0 mole ofthe glass composition, 0.5 to 2.0 mole of MgCO₃, 0.3 to 1.0 mole of rareearth oxide and 0.05 to 1.0 mole of MnO, where the rare earth oxide isat least one selected from the group consisting of Y₂O₃, Ho₂O₃, Dy₂O₃,Yb₂O₃.

According to yet another aspect of the invention for realizing theobject, there is provided a multilayer ceramic capacitor comprising aplurality of dielectric layers, a plurality of internal electrodesalternating with the dielectric layers and external electrodeselectrically connected to the internal electrodes, in which each of thedielectric layers comprises the above-mentioned dielectric compositionof the invention. Preferably, the internal electrodes may contain Ni orNi alloy as a conductor.

According to certain embodiments of the invention, the BaTiO₃ dielectricslurry is sintered uniformly at a low temperature of 1,100° C. or lessto reduce the difference of sintering shrinkage between the internalelectrodes and the dielectric layers. This as a result can restrictconglomeration of the Ni internal electrodes, thereby decreasing shortratio. Furthermore, the multilayer ceramic capacitor can satisfy X5Rdielectric characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a cross-sectional view illustrating a multilayer ceramiccapacitor according to an embodiment of the invention; and

FIG. 2 is a flowchart illustrating a process of fabricating a multilayerceramic capacitor according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will now be described more fully hereinafter.

The inventors have noted an empirical fact that alkali-borosilicateglass forms a liquid phase at a low temperature of 1,000° C. or lesswhile having a high solubility for BaTiO₃, and based on this fact,tested the possibility of alkali-borosilicate system glass as asintering agent for BaTiO3 at a low temperature of 1100° C. or less.According to a glass composition of this invention, adding a suitableamount of alkali earth oxide (at least one of CaO and BaO) into analkali-borosilicate system glass composition, which contains a suitableamount of alkali oxide, makes it possible to stabilize TemperatureCharacteristics Coefficient (TCC) of a multilayer ceramic capacitor andthus to satisfy X5R dielectric characteristics.

Glass Composition

The glass composition of this invention comprises lithium oxide (Li₂O),potassium oxide (K₂O), boron oxide (B₂O₃) and silicon oxide (SiO₂), andoptionally comprises at least one of calcium oxide (CaO) and bariumoxide (BaO).

The content of SiO₂ in the glass composition is in the range from 50mole % to 80 mole % with respect to total 100 mole of Li₂O, K₂O, CaO,BaO, B₂O₃ and SiO₂. The SiO₂ content is preferably in the range of 55mole % to 75 mole %, and more preferably, of 60 mole % to 75 mole %.SiO₂ has an atomic arrangement in which each silicon (Si) atom issurrounded by four oxygen (O) atoms, and connected via the surrounding 0atoms with four adjacent Si atoms. Such SiO₂ is a glass network formeracting as a critical factor for determining major properties of glasssuch as high temperature fluidity, melting point and solubility forBaTiO₃ powder. A SiO₂ content in the glass composition less than 50 mole% leads to poor solubility for the BaTiO₃ powder, thereby failing toimprove low temperature sinterability. On the other hand, when the SiO₂content exceeds 80 mole %, high temperature fluidity becomes poor andliquid is formed at a higher temperature. Thus, the glass composition isnot adequate for sintering agent at a low temperature of 1,100° C. orless.

The content of B₂O₃ in the glass composition is in the range from 5 mole% to 20 mole %. B₂O₃ is a glass network former like SiO₂, acting as animportant factor for determining the solubility of glass composition forthe BaTiO₃ powder. B₂O₃ also acts as a flux to drop the melting point ofglass while improving high temperature fluidity remarkably. Inparticular, for the purpose of improving high temperature fluidity, B₂O₃is preferably added with a content of 5 mole % or more into the glasscomposition. At a B₂O₃ content exceeding 20 mole %, the glass structuremay be weakened thereby degrading chemical stability and glass formingability may be lowered due to crystallization.

The content of Li₂O in the glass composition is in the range from 2 mole% to 10 mole %. Li₂O is a glass network modifier, which acts todisconnect a glass network composed of SiO₂ or B₂O₃, thereby droppingthe melting point of glass while improving high temperature fluidity. ALi₂O content less than 2 mole % may drop high temperature fluidity ofglass but excessively raise liquid forming temperature. At a Li₂Ocontent exceeding 10 mole %, it may be difficult to form glass owing toglass structure weakening and crystallization.

The content of K₂O in the glass composition is in the range from 2 mole% to 10 mole %. Like Li₂O, K₂O is a glass network modifier, which actsto disconnect a glass network composed of SiO₂ or B₂O₃, thereby droppingthe melting point of glass while improving high temperature fluidity. Inparticular, when K₂O is inputted together with other alkali oxide suchas Li₂O, they complement each other (i.e., mixed alkali effect) therebyenhancing chemical endurance of glass while decreasing dielectric lossof dielectric material. At a K₂O content ranging from 2 mole % to 10mole %, glass may have a suitable high temperature fluidity and K₂O mayhave a suitable complementary effect with Li₂O.

CaO and BaO contents in the glass composition is in the range from 0mole % to 25 mole %. CaO is a glass network modifier, which acts to dropthe melting point of glass but enhance the glass structure weakened byalkali metal oxide, thereby enhancing chemical endurance of glass.However, the drawback of CaO is to drop high temperature viscosity ofglass sharply, and thus induce drastic sintering shrinkage to ceramic.BaO can drop the melting point of glass by the largest amount amongalkali earth oxides, and in particular, smoothen high temperaturefluidity variation of glass to prevent abrupt sintering shrinkage ofceramic. CaO and BaO also serve to stabilize capacity temperaturecharacteristics of dielectric material. However, if added by excessiveamount, CaO and BaO may lower sinterability. When at least one of theCaO and BaO contents exceeds 25 mole %, glass forming ability isdegraded and low temperature sinterability of BaTiO₃ dielectric materialis weakened remarkably.

Glass Frit

Glass frit of this invention is composed of the above-mentioned glasscomposition of the invention, and comprises ultra fine spherical powderhaving a particle size ranging from 100 nm to 300 nm. In order to form athin dielectric layer having a thickness of 3 μm or less, a BaTiO₃matrix having a particle size ranging from 150 nm to 300 nm is used in adielectric slurry, and other sub-components except for sintering agentshave a particle size in the range of several hundred nanometers or less.Therefore, when the glass frit added into the dielectric slurry has aparticle size of 1 μm or more, it is difficult to sinter a thindielectric layer uniformly with a thickness ranging from 2 μm to 3 μm.Furthermore, it is preferable to use spherical glass frit since aneedle-shaped or agglomerate glass frit structure may cause nonuniformsintering. The glass frit of this invention can be produced for exampleby mechanically crushing glass flake of the above-mentioned glasscomposition and sequentially performing the vapor phase heat treatment.

A process for fabricating glass frit of this invention will now bedescribed with reference to detailed examples, which are illustrativebut not limiting this invention.

First, constituent powders (Li₂O, K₂O, CaO, BaO, B₂O₃ and SiO₂) areweighed to satisfy the above-mentioned composition of glass, mixedsufficiently, and melted at a temperature ranging from 1,400° C. to1,500° C. The melt is quenched with twin rollers to form glass flake,which is then dry-crushed with a ball mill. Then, vapor phase heattreatment is performed on resultant glass particles to produce glassfrit in the form of ultra fine spherical powder having a particle sizeof 100 nm to 300 nm.

The resultant glass frit is made of the above-mentioned glasscomposition, and can be used as a low temperature sintering agent for amultilayer ceramic capacitor. By using the glass frit of theabove-mentioned glass composition as a sintering agent, a BaTiO3dielectric layer can be uniformly sintered at a low temperature of1,100° C. or less.

Dielectric Composition

The dielectric composition of this invention comprises a main componentof BaTiO₃ and sub-components including glass composition as statedabove, MgCO₃, rare earth oxide and MnO, in which the rare earth oxide isat least one selected from the group consisting of Y₂O₃, Ho₂O₃, Dy₂O₃,Yb₂O₃. The contents of the sub-components are, based on 100 mole of themain component (BaTiO₃), 1.0 to 3.0 mole of the glass composition, 0.5to 2.0 mole of MgCO₃, 0.3 to 1.0 mole of the rare earth oxide and 0.05to 1.0 mole of MnO.

By fabricating a multilayer ceramic capacitor using a dielectriccomposition comprising such components and contents, it is possible torealize a low temperature sintering not exceeding 1,100° C. as well asto ensure capacitance-temperature stability satisfying X5R dielectriccharacteristics.

Multilayer Ceramic Capacitor

FIG. 1 is a cross-sectional view illustrating a multilayer ceramiccapacitor 100 according to an embodiment of the invention. Referring toFIG. 1, the multilayer ceramic capacitor 100 has a capacitor body 110with dielectric layers 102 layered alternately with internal electrodes101 and 103. External electrodes 104 and 105 are formed on the outersurface of the capacitor body 110, and electrically connected tocorresponding internal electrodes 103 and 101, respectively.

The dielectric layers 102 contain the above-mentioned dielectriccomposition of the invention. That is, the dielectric composition of thedielectric layers 102 comprises main component of BaTiO₃ andsub-components including the above-mentioned glass composition. Thesub-components comprise, based on 100 mole of the main component, 1.0 to3.0 mole of the glass composition, 0.5 to 2.0 mole of MgCO₃, 0.3 to 1.0mole of the rare earth oxide and 0.05 to 1.0 mole of MnO.

The thickness of the dielectric layer 102 is not specifically limitedbut may not exceed 3 μm per layer in order to realize an ultra thin,high capacity capacitor. Preferably, the dielectric layer 102 may have athickness ranging from 1 μm to 3 μm. The conductor contained in theinternal electrodes 101 and 103 is not specifically limited. However,since the dielectric layer 102 itself is reduction resistant, Ni or Nialloy may be preferably used for the internal electrodes 101 and 103. Cuor Ni may be used for the external electrodes 104 and 105.

The multilayer ceramic capacitor 100 may be fabricated by a processsimilar to that of a conventional ceramic capacitor, which includesslurry preparation, green sheet forming, internal electrode printing,layering, compression, sintering and so on.

Hereinafter the process for fabricating a multilayer ceramic capacitoraccording to an embodiment of the invention will be described in detailwith reference to FIG. 2. In steps S1 and S1′, BaTiO₃ powder of maincomponent and sub-component powers are prepared, respectively, byweighting them to satisfy the above-mentioned glass composition anddielectric composition. In detail, the sub-component powders comprise,based on 100 mole of the main component of BaTiO₃, 1.0 to 3.0 mole ofthe glass composition, 0.5 to 2.0 mole of MgCO₃, 0.3 to 1.0 mole of rareearth oxide and 0.05 to 1.0 mole of MnO. The glass composition isexpressed by a formula: aLi₂O-bK₂O-cCaO-dBaO-eB₂O₃-fSiO₂, wherea+b+c+d+e+f=100, 2≦a≦10, 2≦b≦10, 0≦c≦25, 0≦d≦25, 5≦e≦20, and 50≦f≦80,and the rare earth oxide is at least one selected from the groupconsisting of Y₂O₃, Ho₂O₃, Dy₂O₃, Yb₂O₃. Here, the glass composition maybe provided as glass frit in the form of ultra fine spherical powderhaving a particle size of 100 nm to 300 nm. Then, the weighed powdersare mixed and dispersed into an organic solvent in step S2, into whichan organic binder is additionally mixed to prepare a dielectric slurryin step S3. The organic binder may adopt polyvinyl butyral, and thesolvent may adopt acetone or toluene.

Then, the slurry is formed into (green) sheets in step S4. For example,the slurry may be formed into green sheets having a thickness of 3 μm orless. Then, internal electrodes of for example Ni are printed on thegreen sheets, and the green sheets printed with the internal electrodesare layered one atop another in step S5. In step S6, a stack of thegreen sheets are compressed and cut into separate chips (or greenchips). Then in step S7, the green chips are heated at a temperatureranging from 250° C. to 350° C. to remove binder or dispersing agenttherefrom.

With the binder removed, the stacks or green chips are sintered (fired)at a temperature ranging from 1,100° C. or less in step S8. Here, at afiring temperature exceeding 1,150° C., an internal electrode may beseparated from a dielectric layer or a Ni electrode layer may form aconglomerate as in the prior art. This is directly associated withdelamination of the internal electrode, which in turn reducesreliability. Accordingly, this invention preferably limits the sinteringtemperature not exceeding 1,100° C.

Then, paste for external electrode such as Cu and Ni is printed on theoutside surface of the sintered stacks, and then fired to form externalelectrodes in step S9. A coat may be formed optionally on the externalelectrodes via plating in step S10. As a result, multilayer ceramiccapacitors 100 as shown in FIG. 1 are fabricated. Then, the qualities ofthe multilayer ceramic capacitors may be evaluated by measuring severalproperties of the capacitors in step S11.

The inventors have found empirically, through various experiments, thatthe multilayer ceramic capacitors of the invention satisfy X5Rcharacteristics and have excellent electric characteristics when madefrom the above-mentioned glass composition and dielectric composition.

EXAMPLES

This invention will be described in more detail with reference tofollowing Examples, which are illustrative but not limiting. In thefollowing Examples, before fabrication of commercially distributablechips having more layers (e.g., several hundred layers or more),specimens were made first with fewer layers of about 10 layers toobserve their properties.

In order to produce glass having a composition ofaLi₂O-bK₂O-cCaO-dBaO-eB₂O₃-fSiO₂, where a+b+c+d+e+f=100, 2≦a≦10, 2≦b≦10,0≦c≦25, 0≦d≦25, 5≦e≦20, and 50≦f≦80, corresponding elements were weighedand mixed sufficiently to satisfy the composition of Table 1 below, andmixtures were melted at a temperature ranging from 1,400° C. to 1,500°C. Then, the melts were quenched with twin rollers to produce glassflakes, which were then dry-crushed and then subjected to vapor phaseheat treatment to produce glass frits in the form of ultra finespherical powder having a particle size of 100 nm to 300 nm. At the sametime, a glass frit without an alkali oxide (such as Li₂O and K2O) wasprepared as a Comparative Example.

TABLE 1 Composition of glass frit (mol %) Alkaline-earth Alkaline oxideoxide Network former Glass frit no. Li₂O K₂O CaO BaO B₂O₃ SiO₂ InventiveA1 7 3 10 5 75 A2 5 5 10 5 75 A3 3 7 10 5 75 A4 7 3 20 5 65 A5 7 3 5 155 65 A6 7 3 10 10 5 65 A7 7 3 15 5 5 65 A8 7 3 20 5 65 A9 7 3 15 15 60A10 7 3 10 15 65 A11 7 3 5 15 70 A12 7 3 0 15 75 A13 7 3 20 10 60 A14 73 20 15 55 A15 7 3 20 20 50 Comp. A16 25 25 50

Then, the sub-components including the glass frits were weighed as inTable 2 below, and mixed and dispersed into an organic solvent.

TABLE 2 Sub-components (mol % with respect to 100 Main mol of maincomponent) compo- Rare Sintering nent earth agent No. BaTiO₃ MgCO₃ oxideMnO Type Cont. Comp. 1 100 1.5 1.0 0.3 A16 1.5 2 100 1.5 1.0 0.3 BaSiO₃1.5 3 100 1.0 0.7 0.1 A4 3.1 4 100 1.0 0.7 0.1 A5 3.2 5 100 1.0 0.7 0.1A6 3.2 6 100 1.0 0.7 0.1 A7 0.8 7 100 1.0 0.7 0.1 A8 0.8 8 100 1.0 1.00.3 A13 0.9 Inventive 1 100 1.5 1.0 0.3 A9 1.5 2 100 1.5 1.0 0.3 A9 2.03 100 1.5 1.0 0.3 A10 1.5 4 100 1.5 1.0 0.3 A10 2.0 5 100 1.5 1.0 0.3A11 1.7 6 100 1.5 1.0 0.3 A11 2.0 7 100 1.5 1.0 0.3 A12 1.5 8 100 1.51.0 0.3 A12 1.8 9 100 1.0 1.0 0.3 A14 1.5 10 100 1.0 1.0 0.3 A15 1.5(Rare earth oxide is one of Y₂O₃, Ho₂O₃ and Yb₂O₃)

Then, an organic binder was additionally mixed to produce slurries,which were then printed on films to a thickness of about 5 μm tofabricate dielectric sheets. Next, internal electrodes of Ni wereprinted, and the dielectric sheets printed with the internal electrodeswere stacked on atop another up to 10 layers. Dielectric sheets withoutany internal electrodes were layered on the top and bottom of the sheetstacks. The stacks were subjected to Cold Isostatic Press (CIP) at atemperature of about 85° C. under a pressure of 1,000 kg/cm² for about15 mins, and then cut into specimens. The specimens were heat treated ata temperature ranging from 250° C. to 350° C. for 40 hours or more tofire and remove the organic binder, a dispersant and so on, and sinteredin various temperatures ranging from 1,050° C. to 1,200° C. with anelectric furnace controllable in temperature and atmosphere. Here,oxygen partial pressure in the sintering atmosphere was controlled inthe range from 10⁻¹¹ to 10⁻¹² atm. After sintering, the specimens wereprinted with external electrodes of Cu, and subjected to electrodefiring at a temperature ranging from 850° C. to 920° C., followed byplating, thereby completing specimen fabrication. After a predeterminedtime duration, electric properties of the fabricated specimen weredetermined.

The electric properties of the specimens were determined by measuringcapacitance and dielectric loss under conditions of 1 KHz and 1 Vrmswith a capacitance meter (Agilent, 4278A) and measuring insulationresistance under a rated voltage for 180 secs with a high resistancemeter (Agilent, 4339B). Furthermore, temperature dependency ofdielectric constant was measured based on variations in the range from−55° C. to 135° C. with a Temperature Characteristics Coefficient (TCC)test chamber (4220A). Dielectric constants according to the sinteringtemperatures were calculated based on the thickness of dielectric layersafter being sintered. In the meantime, a high temperature load test wascarried out by applying a DC voltage of 18.9 V at 150° C. and measuringthe aging rate of insulation resistance. Test results are reported inTable 3 below.

TABLE 3 TCC ST DL Res (85° C.) No. (° C.) DC (%) (Ωm) (%) Remarks Comp.1 1200 2800 6.7 6.7*10⁹ −11.2 1150 — — — — Not sintered 2 1150 2900 4.58.7*10⁸ −8.6 1100 — — — — Not sintered 3 1150 3450 10.9 7.9*10⁶ 15.2Abnormal grain growth 1100 2340 6.6 5.7*10⁵ −4.5 Not sintered 4 11002410 7.3 3.4*10⁶ −1.9 Not sintered 5 1100 2680 8.1 4.4*10⁶ 1.4 Notsintered 6 1100 2380 11.9 3.9*10⁶ −1.7 Not sintered 7 1100 2170 12.110.7*10⁷  −1.1 Not sintered 8 1100 2420 8.8 9.2*10⁶ −4.7 Not sinteredInventive 1 1120 3150 7.8 3.9*10⁹ 2.7 2 1100 3015 7.4 2.7*10⁹ 0.1 3 11003400 6.1 6.2*10⁹ −3.2 4 1070 3200 5.9 5.9*10⁹ −4.2 5 1100 3250 7.16.1*10⁹ 1.2 6 1060 3150 6.8 3.7*10⁹ −2.4 7 1100 3550 7.2 6.9*10⁹ −1.8 81060 3310 6.7 5.2*10⁹ −2.9 9 1100 3050 6.4 2.9*10⁹ −4.8 10 1070 2800 6.18.9*10⁹ −1.8 Note) ST: Sintering Temperature DC: Dielectric Constant DL:Dielectric Loss Res: Resistivity

As seen in Table 3 above, Examples 2 to 10 of this invention showedexcellent sinterability at a low temperature of 1,100° C. or less.Especially, in Examples 3 to 9, dielectric constant and resistivity wereexcellent and TCC of capacitance was very stable. Accordingly, anycommercially available capacitors with 400 layers or more, whenfabricated from the specimens of Examples 2 to 10, are expected tosatisfy X5R characteristics (−55° C. to 85° C., ΔC=±15% or less) also.These results of Inventive Examples are comparable with those ofComparative Examples 1 and 2 fabricated by using BaO—CaO—SiO₂ glass fritor BaSiO₃ system mixed powder, in which the specimens showed lowsinterability at a temperature of 1,150° C. or less, and foundunsuitable for sintering at a temperature of 1,100° C. or less.

While the present invention has been described with reference to theparticular illustrative embodiments and the accompanying drawings, it isnot to be limited thereto but will be defined by the appended claims. Itis to be appreciated that those skilled in the art can substitute,change or modify the embodiments into various forms without departingfrom the scope and spirit of the present invention.

As set forth above, with the glass frit of the present invention, BaTiO₃layers can be uniformly sintered at a low temperature of 1,100° C. orless. This as a result reduces sintering shrinkage difference betweenthe dielectric layers and internal electrode layers as well as restrictNi conglomeration, thereby minimizing internal electrode delamination.Moreover, a resultant multilayer ceramic capacitor can satisfy excellentelectric characteristics together with X5R dielectric characteristics(EIA standards: −55° C. to 85° C., ΔC=15% or less).

1. A glass composition comprising aLi₂O-bK₂O-cCaO-dBaO-eB₂O₃-fSiO₂,wherein a, b, c, d, e and f satisfy following relationships:a+b+c+d+e+f=100, 2≦a≦10, 2≦b≦10, 0≦c≦25, 0≦d≦25, 5≦e≦20, and 50≦f≦80. 2.The glass composition of claim 1, wherein a, b, c, d, e and f satisfyfollowing relationships: 3≦a≦8, 2≦b≦5, 0≦c≦15, 0≦d≦15, 10≦e≦20, and55≦f≦75.
 3. The glass composition of claim 1, wherein a, b, c, d, e andf satisfy following relationships: 3≦a≦8, 2≦b≦5, 0≦c≦15, 5≦d≦15,12.5≦e≦17.5, and 60≦f≦75.
 4. A glass frit of a glass compositionexpressed by a formula: aLi₂O-bK₂O-cCaO-dBaO-eB₂O₃-fSiO₂, wherea+b+c+d+e+f=100, 2≦a≦10, 2≦b≦10, 0≦c≦25, 0≦d≦25, 5≦e≦20, and 50≦f≦80,the glass frit comprising ultra fine spherical powder having a particlesize ranging from 100 nm to 300 nm.
 5. The glass frit of claim 4,wherein a, b, c, d, e and f satisfy following relationships: 3≦a≦8,2≦b≦5, 0≦c≦15, 0≦d≦15, 10≦e≦20, and 55≦f≦75.
 6. The glass frit of claim4, wherein a, b, c, d, e and f satisfy following relationships: 3≦a≦8,2≦b≦5, 0≦c≦15, 5≦d≦15, 12.5≦e≦17.5, and 60≦f≦75. 7-13. (canceled)